This application pertains to the art of valves and spigots and, more particularly, to drain valves. The invention is particularly applicable to drain valves for hot water heaters and will be described with particular reference thereto. It will be appreciated, however, that the invention has other applications such as sillcocks, spigots, other drain valves, and the like.
Hot water heaters conventionally have an iron or steel water tank with an inner glaze or lining. Near the bottom, the tank has an internally threaded metallic female fitting for receiving a drain valve. The drain valves must be strong and leak resistant even at the elevated temperatures associated with the hot water tank, generally on the order of 140.degree. F. or more. Many homeowners use the drain valves only after long intervals, such as a year or two, to drain sediment from the tank. When drain valves remain closed for long periods, sufficient sediment may accumulate in the tank to clog the inlet to the drain valve. Sediment clogs are most easily broken up in drain valves which are designed such that a rod or snake can pass into the clog without removing the valve.
Other homeowners use the drain valve of their hot water tank frequently as a source of hot water. A hot water tank drain valve must be reliable whether used frequently or infrequently and when subject to relatively high temperatures and should readily receive rods for dislodging accumulated sediment.
Heretofore, drain valves have had a linear central bore with an outlet through the center of the handle. A commonly used drain valve of this configuration is illustrated in U.S. Pat. No. 3,181,555, issued May 4, 1965 to I. D. Jacobson. When using such valves, the homeowner risks discharging hot water through the handle into his hand.
Conventional sillcocks and other valves have also been used as drain valves on hot water tanks but have several drawbacks. When brass or copper valves are connected with the steel water tank, a galvanic interaction occurs causing corrosion and eventual failure. Another drawback to conventional sillcocks is that they inhibit the introduction of a rod or shank for dislodging sediment blockages. Removing the valve stem to provide a rod or snake receiving path is somewhat complex and introduction of a rod or snake is virtually impossible. Generally, it involves removing the handle from the valve stem, the bonnet from the valve body, and then removing the valve stem. Removing the bonnet risks interfering with the packing or seal between the bonnet and valve stem. Further, even after removing the valve stem, many valves present nonlinear or event tortuous paths which do not readily accept a rod or snake. Exemplary sillcocks are illustrated in U.S. Pat. No. 3,386,700, issued June 4, 1968 to G. Z. Greene et al. and U.S. Pat. No. 4,022,243, issued May 10, 1977 to R. B. Edwards. Valves have also been suggested in which the bonnet or other stem retainer is readily removable, note for example, U.S. Pat. No. 4,064,900, issued Dec. 7, 1977 to W. C. Schmitt and U.S. Pat. No. 1,518,307, issued Dec. 9, 1924 to G. W. Cooke.
The present invention contemplates a new and improved drain valve which overcomes all of the above-referenced problems and others. It provides a drain valve which is economical to manufacture, highly reliable whether used frequently or infrequently, and provides ready access through the valve for loosening sedimentation. Further, the valve of this invention eliminates the possibility of galvanic corrosion due to its non-metallic construction.